The present invention relates to a clutch actuation device as described hereinafter.
Clutch actuation devices are already known wherein actuation of a shift mechanism is not directly effected by mechanical means by way of the clutch pedal but the shifting movement is performed by a pneumatic or hydraulic actuating device in response to electric control signals from a control unit. These control signals are, in turn, formed on the basis of the engine speed, load and the disengaging position at the clutch. Devices of this type are used primarily in vehicles with semi-automatic gear systems where the gears are still shifted in the normal manner by the driver but where the shifting process only requires the actuation of a switchcontact on the part of the driver. The actual "proportioning of power" to the clutch, which is particularly important during initial acceleration of the vehicle, is then performed exclusively by the control unit and can no longer be influenced by the driver.
The advantage of the above-described systems over the conventional systems operated exclusively by the driver is that they offer increased ease of use without the disadvantage of the high production costs of fully automatic gears.
However, the advantage of the ease of use of the above clutch actuation systems is somewhat outweighed by the disadvantage that the driver has no input in critical driving situations, particularly in the proportioning of power to the clutch.
It is also known (U.S. Pat. No. 4,491,919), in the case of a locking protection control system (LPCS) equipped vehicle with a service-brake configuration to break the drive connection to the drive wheels via a multi-way magnetic valve by an appropriate application of pressure on the coupling cylinder simultanously with the onset of the LPCS regulating action on the brake system, i.e., to disengage in order to interrupt, at least temporarily, any braking action by the i.c. engine on the wheels driven by the same. As a result, opposing influences can be reliably avoided. Re-engagement is not controlled by the driver but is preferably time-controlled to avoid a coupling jolt.